Absorption cooling machine

Abstract

The present invention relates to a machine for cooling by absorption, comprising a desorber / condenser assembly comprising a refrigerant and absorbent desorber, a refrigerant condenser and an evaporator / absorber assembly. The machine comprises a first pump designed to recover a solution from the absorber, a second pump designed to recover the refrigerant from the evaporator, and a third pump designed to recover a weakened solution from the absorber and pass it through a third exchanger in which the weak solution is heated before being directed toward a fourth exchanger where the weak solution continues to be heated before being directed towards the desorber. The first exchanger is arranged between the first pump and the absorber gratings and is configured to form a siphon for the absorbent, thus preventing the passage of air, the machine having no electric valve.

Description

[0001] The present invention relates to an absorption cooling machine comprising means for reducing energy consumption and increasing efficiency.

[0002] Absorption machines are very common thermal cooling systems.

[0003] Absorption machines work thanks to the ability of certain liquids to absorb and desorb vapor. The mixture of these two substances is called a binary mixture. By placing them next to each other, the evaporating substance cools down, and the absorbing substance heats up. This is the exothermic effect. The absorbing component is called the absorbent, while the desorbing component, which is highly volatile, is the refrigerant or evaporant.

[0004] Two pairs are mainly used even if other solutions exist although they are too expensive, too complicated or too polluting. The first is the water and ammonia (NH3) solution, where water is the absorbent and ammonia is the evaporant. This solution allows cooling down to -24° Celsius with a heating of 160° Celsius and pressures up to 20 atmospheres. The second solution is the water and Lithium Bromide (H20-LiBr) mixture, water being the evaporant and lithium bromide the absorbent. With the latter it is possible to cool down to 1° Celsius with a heating (in currently operating machines) of 90° Celsius, at pressures between 6 mb and 85 mb (vacuum).

[0005] This solution is based on the triple point of water; at approximately 6 mb water is solid, liquid, gas (vapor), and at a temperature of 0° Celsius. In other words, at 6 mb of pressure water boils at 0° Celsius.

[0006] So, it is enough to keep the water at 6 mb for it to remain at 0°. The pressure in which we live is on average 1010 mb. We must therefore work in a vacuum. Researchers such as William Cullen in 1755, Gerald Nairme in 1777, John Leslie in 1810, the French Edmond and Ferdinand Carré in 1859 achieved this, which today has the effect of democratizing the principle of cold by absorption.

[0007] The patent application published by the French National Institute of Intellectual Property under number FR1298366A describes an absorption refrigeration system comprising a generator, a condenser, an absorber and a refrigerant evaporator. The generator can heat the dilute solution it contains to produce refrigerant vapors and a concentrated solution. The refrigerant vapors produced in the generator pass into the condenser. The condensates formed in the condenser pass into the evaporator where they are cooled by expansion, the vapors resulting from this expansion in the evaporator passing into said absorber to be absorbed there. The absorption refrigeration system further comprises a solution evaporator communicating with the generator and receiving the concentrated solution and a second absorber in which a pressure intermediate between those of the generator and the first absorber prevails.The pressure in the solution evaporator is substantially equal to the pressure in the second absorber, the solution in the solution evaporator being cooled there by expansion upon entering, the vapor resulting from this expansion passing into the second absorber to be absorbed by the solution it contains, this second absorber being in communication with the first absorber to receive the solution it contains and with the generator to supply it with solution. Depending on the liquids that are chosen as absorbent and as refrigerant, it is possible for crystals to form in the absorbent solution, which can lead to a breakdown. It is therefore necessary to increase the reliability of absorption cooling machines.

[0008] EP1210556 describes a system for producing cold by absorption comprising a generator, a condenser, an evaporator, an expansion valve and an absorber and a pressurized refrigerant liquid storage assembly composed of at least one tank, a valve upstream of said tank and a valve downstream of said tank. The upstream valve is open when the pressure at the outlet of the condenser is greater than or equal to the pressure in the tank and the downstream valve is blocked as soon as the generator stops producing steam.

[0009] Moreover, the applicant has perfected the absorption system to the point where it can now produce cold using solar energy or even hot water from a car, i.e. using free energy.

[0010] The aim of the present invention is therefore to propose an absorption cooling system which has the advantage of providing much higher efficiencies than conventional systems and whose construction is simplified.

[0011] Thanks to the machine of the present invention, it is possible to produce intense cold, even at full capacity, with water heated between 60° Celsius and 75° Celsius, unlike the machines on the market which operate at 90° Celsius.

[0012] According to the invention, an absorption cooling machine comprises a desorber / condenser assembly comprising a refrigerant fluid desorber and absorbent fluid by separation of a mixed flow, a refrigerant fluid condenser connected to the desorber. The machine comprises an evaporator / absorber assembly, the refrigerant fluid absorber being arranged to absorb the evaporated refrigerant fluid coming from the evaporator, the absorber being connected to the condenser by an absorbent fluid supply line and by a mixed fluid discharge line.The machine further comprises a first pump arranged to recover a solution from the absorber and pass it into a first exchanger where the solution cools before being directed to grids of the absorber, a second pump arranged to recover the refrigerant from the evaporator and pass it into a second exchanger where it cools the refrigerant, before directing it to grids of the evaporator, and a third pump arranged to recover a depleted solution from the absorber and pass it into a third exchanger in which the lean solution heats up before being directed to a fourth exchanger where the lean solution continues to heat up before being directed to the desorber. The machine also comprises an electronic card arranged to control the amperage of the pumps and cut off the heating if the amperage reaches a critical threshold, typically 1.8A.The first exchanger is arranged between the first pump and the absorber grids and configured to form a siphon for the absorbing fluid, thus preventing the passage of air, the machine having no solenoid valve.

[0013] The characteristics of the invention will appear more clearly on reading a description of an embodiment given solely by way of example, in no way limiting, by referring to the schematic figures, in which: There Figure 1 represents an absorption machine with its protective cover removed; The Figure 2A represents a perspective view in partial transparency of the desorber / condenser assembly of the machine of the figure 1 ; There figure 2B represents a perspective view of two plates of the desorber / condenser assembly of the figure 2A ; There figure 2C represents a partial view of a splash plate of the desorber / condenser assembly of the figure 2A ; There figure 2D represents a partially transparent view of a condenser of the desorber / condenser assembly of the figure 2A ; There Figure 3A represents a perspective view of the evaporator / absorber assembly of the Figure 1 ; There figure 3B represents a side view of a grid of the evaporator / absorber assembly of the figure 3A ; There figure 3C represents a perspective view of a liquid receiving channel of the grids of the evaporator / absorber assembly of the figure 3A ; and The figures 4 And 5 represent a schematic view of the rear of the machine according to the present invention.

[0014] According to the preferred embodiment of the invention as illustrated in the Figure 1 , the absorption cooling machine uses a mixed fluid composed of lithium bromide which acts as an absorbent and water which acts as a refrigerant. The absorption cooling machine comprises a desorber / condenser assembly 1 comprising a desorber 2 ( figure 2A ) of refrigerant fluid and absorbent fluid by separation of a mixed flow and a condenser 3 ( figure 2A ) of refrigerant fluid connected to the desorber 2. The machine comprises an evaporator / absorber assembly 4, the refrigerant fluid absorber 5 being arranged to absorb the evaporated refrigerant fluid coming from the evaporator 6, the absorber being connected to the condenser by an absorbent fluid supply line and by a mixed fluid discharge line.

[0015] The machine comprises a first pump P1 arranged to recover a solution from the absorber 5 and pass it into a first exchanger ECH1 where the solution cools before being directed towards grids 7 (see figure 3A ) of absorber 5. It is pump P1 which is magnetically driven and which triggers the alarm to an electronic card in the event of an overly rich solution. The flow rate of this pump P1 is approximately equal to 1500L / H.

[0016] A second pump P2 is arranged to recover the refrigerated water from the evaporator 6 and pass it into a second exchanger ECH2 where it refrigerates the air conditioning liquid, before directing this cooled water to grilles 8 (see figure 3A ) of the evaporator. The flow rate of this pump P2 is approximately equal to 1500L / H.

[0017] A third pump P3 is arranged to recover a lean solution from the absorber 5 and pass it into a third exchanger ECH3 in which the lean solution heats up before being directed to a fourth exchanger ECH4 where the lean solution continues to heat up before being directed to the desorber 2.

[0018] An electronic card 9 (see figure 1 ) is designed to control the amperage of pumps P1, P2, P3 and cut off the heating if the amperage reaches a critical threshold, typically 1.8A. At the threshold value of 1.8A, the electronic card triggers the heating to stop and cuts off the pump. This prevents the crystallization of Lithium Bromide.

[0019] The first exchanger ECH1 is arranged between the first pump P1 and the grids 7 of the absorber 5 and configured to form a siphon for the absorbent fluid, thus preventing the passage of air, the machine having no solenoid valve. The siphon is arranged to avoid the control valves. Water-saturated lithium bromide is sent to the desorber / condenser assembly. The additional water evaporates in the condenser and goes back down into the evaporator. The lithium bromide that has evaporated the additional water goes back down into the absorber. The pressure is 85 mbar in the desorber / condenser assembly and 10 mbar in the evaporator / absorber. The risk is that, without control, the water will come in but also the steam. The siphon is created for this purpose. The pressure difference of 75 mbar requires the creation of a 75 cm long siphon. For example, with a pressure difference of 60mbar, a siphon length of 60cm would be sufficient.The siphon length is therefore proportional to the pressure difference between the desorber / condenser and the evaporator / absorber. Thanks to this device, it is possible to maintain control of the water coming back down from the condenser.

[0020] The first, second and third pumps P1, P2, P3 are magnetic drive pumps and the third pump P3 is a magnetic drive gear pump.

[0021] As illustrated in figures 4 And 5, the third magnetic drive pump P3 is a gear pump. It ensures a flow rate of 200L / H in vacuum but remains at 200L / H at 10atm which guarantees a high flow rate regularity, recommended in the context of the present invention. The third magnetic drive pump P3 receives the lean solution from the absorber, directs it to the third exchanger ECH3 in which it crosses the rich solution which descends from the desorber at a high temperature. Thus, the lean solution heats up and the rich solution cools down. At the outlet of the third exchanger ECH3, the lean solution goes to the fourth exchanger ECH4 where it crosses the heating water which leaves the desorber. It heats up subsequently and arrives in the desorber ready to desorb.

[0022] As illustrated in figures 2A et 2B , the desorber / condenser assembly 1 comprises two desorption plates 10, 11 superimposed and inclined relative to each other, typically approximately 4% slope, the flow surface area of ​​the two plates 10, 11 being slightly greater than the surface area of ​​an inlet connection 20 of the plates 10, 11, an anti-splash plate 12 (see figure 2C ) comprising flat, parallel slats, the slats being fixed together by long blades arranged on either side of each slat so as to allow the steam to pass through but stop the droplets of the absorbent solution.

[0023] As illustrated in the figure 2D , the desorber / condenser assembly 1 comprises a vertical condensation plate 13 of which a cooling water inlet 23 is positioned lower than a cooling water outlet 24, the flow area of ​​the internal channels of the condenser being slightly greater than the area of ​​an inlet connection. The condenser comprises small separation plates 25 used to orient the direction of flow.

[0024] As illustrated in the figure 3A , the evaporator / absorber assembly 4 is connected to a circuit for circulating a binary mixture comprising a first refrigerant and a second absorbent fluid, the refrigerant being evaporated in an evaporator part of the evaporator / absorber assembly 4 and then absorbed in an absorber part of the evaporator / absorber assembly 4 by the mixture rich in absorbent fluid. The evaporator / absorber assembly 4 comprises two distributor tubes 14, 15 facing each other forming evaporator 6 and absorber 5 members, refrigerant diffusers 16 and absorbent fluid-rich mixture diffusers 17, each refrigerant diffuser being arranged alternately with a diffuser of the mixture rich in absorbent fluid.

[0025] The evaporator comprises a plurality of grids 26 (see figure 3B ) and a reception channel 27 (see figure 3C) of liquid from the grids 26. The grids 26 are arranged vertically in the evaporator / absorber assembly 4 in parallel planes spaced transversely. Each grid 26 extends from one edge of a distributor to another edge of the opposite distributor. Each grid 26 is engaged in the receiving channel 27 and fixed in its middle by weld points. In this example, the weaving of the water grids is 14 / 100.200 while the weaving of the lithium bromide grids is 25 / 118.114.

[0026] Each receiving channel 27 of the evaporator / absorber assembly 4 allows the selective recovery of liquids by gravity.

[0027] The water molecule being finer than that of lithium bromide, the grids 26 of the evaporator are finer than the grids 26 of the absorber, thus allowing the liquid to be retained and the vapor to pass through.

[0028] At the inlet of the absorber and the evaporator, another grid 7 and yet another grid 8 are arranged a few millimeters from the walls, for example 5 mm, so as to avoid splashing of the rich solution or water when one, the lithium bromide, enters the absorber and the other, the water, enters the evaporator.

[0029] To produce about 10 kW / h of cold, it is necessary to evaporate, absorb, desorb and condense about 20 liters of water / hour. By circulating 200 l / h of 56% solution (about 1620 gr / liter) between the absorber and the desorber, to produce 10 kW / h of cold, it is necessary to subtract about 20 liters of water (20,000 gr) from the (1620 gr x 200 liters - 324,000 gr) of 56% solution in circulation, therefore desorbing and condensing 20,000 gr of water.

[0030] Thus, at the exit of the desorber there will be 324,000gr - 20,000gr or 304,000gr for 180 liters of solution.

[0031] That is to say a solution which will weigh 304,000 gr / 180 liters = 1688.80 gr / l or approximately 59% Lithium Bromide.

[0032] This is an ideal result.

[0033] Thanks to the machine of the present invention, this result is obtained with a temperature at the absorber of 30° and a heating at the desorber of 75°. But, if the solution is above 35° at the absorber, to obtain a good result, the concentration of Lithium Bromide must be 59%, that is to say approximately 1690 gr x 200 = 338,000 gr of solution and it is necessary to desorb 20l (20,000gr) of water and to lower (338,000gr - 20,000gr) / 180 liters that is to say a solution which will weigh 1766.67gr / liter at approximately 63% concentration. In this configuration, the threshold of crystallization is reached.

[0034] Crystallization is due to an excessive concentration of Lithium Bromide in the solution because the machine desorbs more than it absorbs. Generally, due to excessive pressure in the evaporator due to a leak or the formation of non-condensables, the machine no longer evaporates, does not absorb and continues to desorb until failure.

[0035] The machine of the present invention solves this problem. We observed that the amperage of the solution pump increased by 2.5 / 10 when the solution went from 54% to 61% so that when the amperage increases beyond 2.5 / 10 the heater automatically blocks and triggers the alarm thus preventing crystallization. For example, the amperage has a value of 1.5A at 54%, 1.6A at 58% and 1.75A at 60%.

[0036] Flow control is important. Water and Lithium Bromide should never flow at more than 5km / h. At 54% the solution weighs about 1600gr / liter, its fluidity is not ideal and as the concentration increases the fluidity decreases and at 65% it is crystallization. Thus, to avoid crystallization, a flow rate of about 1500 l / h of water from 1 / 2" (12.7mm inner diameter) tubes is sufficient. With the same flow rate for the solution it will be necessary to use 3 / 4" (19.5mm inner diameter) tubes.

[0037] The machine of the present invention is designed to operate with solar energy as well as with a standard electrical network. Its operation is simplified insofar as all solenoid valves are eliminated thanks to the use of siphons.

[0038] Thanks to the machine of the present invention, it is possible to produce intense cold with water heated without bringing it to a boil, that is to say from a temperature of around 60° which facilitates in particular the operation of the machine with solar energy.

Claims

1. Absorption cooling machine comprising: - a desorber / condenser assembly (1) comprising: - a refrigerant and absorbent fluid desorber (2) by separation of a mixed flow; - a refrigerant condenser (3) connected to the desorber (2); - an evaporator / absorber assembly (4), the refrigerant absorber (5) being arranged to absorb the evaporated refrigerant from the evaporator (6), the absorber (5) being connected to the condenser (3) by an absorbent fluid supply pipe and a mixed fluid discharge pipe, - a first pump (P1) arranged to recover a solution from the absorber (5) and pass it through a first exchanger (ECH1) of the cooling machine where the solution is cooled before being directed toward grilles (7) of the absorber (5), - a second pump (P2) arranged to recover the refrigerant from the evaporator (6) and pass it through a second exchanger (ECH2) where it cools said refrigerant, before directing it toward grilles (8) of the evaporator (6), - a third pump (P3) arranged to recover a weakened solution from the absorber (5) and pass it through a third exchanger (ECH3) in which the weak solution is heated before being directed toward a fourth exchanger (ECH4) where the weak solution continues to be heated before being directed toward the desorber (2), - an electronic board (9) arranged to control the amperage of the pumps (P1, P2, P3) and to stop the heating if the amperage reaches a critical threshold, typically 1.8A, wherein the first exchanger (ECH1) is arranged between the first pump (P1) and the grilles (7) of the absorber (5) and configured to form a siphon for the absorbent fluid, thereby preventing the passage of air.

2. Cooling machine according to claim 1, wherein the first, second and third pump (P1, P2, P3) are magnetic drive pumps and of which the third pump (P3) is a magnetic drive gear pump.

3. Cooling machine according to claim 1 or 2, wherein the desorber / condenser assembly (1) comprises two desorber plates (10, 11) superposed and inclined with respect to one another, typically with a slope of about 4%, the flow area of internal channels of the two plates (10, 11) being slightly greater than the area of an inlet connection of the plates (10, 11) allowing the passage of a fluid, an anti-splash plate (12) comprising flat slats which are parallel to one another, the slats being secured to one another by long strips arranged on either side of each slat so as to let vapor through but to stop droplets of the absorbent solution.

4. Cooling machine according to one of the preceding claims, wherein the desorber / condenser assembly (1) comprises a vertical condensation plate (13), a cooling water inlet of which is positioned lower than a cooling water outlet, the flow area of the internal channels of the condenser being slightly greater than the area of an inlet connection.

5. Cooling machine according to one of the preceding claims, wherein the evaporator / absorber assembly (4) is connected to a circuit for circulating a binary mixture comprising a first refrigerating fluid and a second absorbent fluid, the refrigerating fluid being evaporated in an evaporator part of the evaporator / absorber assembly (4) and then absorbed in an absorber part of the evaporator / absorber assembly (4) by the mixture which is rich in absorbent fluid.

6. Cooling machine according to claim 5, wherein the evaporator / absorber assembly (4) comprises two distributor tubes (14, 15) facing each other forming evaporator (6) and absorber (5) members, refrigerating fluid diffusers (16) and diffusers (17) of the mixture rich in absorbent fluid, each refrigerating fluid diffuser being arranged alternately with a diffuser of the mixture rich in absorbent fluid.

7. Cooling machine according to one of the preceding claims, wherein the refrigerant is water and the absorbent fluid is lithium bromide.

8. Cooling machine according to one of the preceding claims, wherein the evaporator (6) comprises a plurality of grilles (26) arranged vertically in the evaporator / absorber assembly (4) in transversely spaced parallel planes.

9. Cooling machine according to claim 8, wherein each grille (26) is engaged in a receiving channel (27) secured in the middle thereof by welding points, each receiving channel (27) is arranged to recover the liquids by gravity.

10. Cooling machine according to claim 8 or 9, wherein the evaporator grilles (26) are finer than the absorber grilles (26), thus allowing liquid to be retained and vapor to pass through, typically a mesh of 14 / 100.200 for the evaporator grilles, and a mesh of 25 / 118.114 for the absorber grilles.

11. Cooling machine according to one of claims 8 to 10, wherein at the inlet of the absorber and of the evaporator, a further grille (7) and a still further grille (8) are arranged a few millimeters from the walls, transversely to the grilles (26) of the evaporator and of the absorber, so as to prevent splashing of the solutions when one enters the absorber and the other enters the evaporator.

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